The M’nos HaLevi writes that the wicked are simply never satisfied.
The Talmud (Megillah 15b) says Haman was called a slave who sold himself for bread, referring to the famous Midrash the Haman sold himself into slavery to Mordechai when the two of them were generals and the supplies with which the king entrusted Haman ran out.
How do Mordechai’s actions take away from Haman’s list of honors? Rashi writes that Haman forgot about his honor whenever he saw Mordechai. R’ Dovid Feinstein writes that this occurs naturally to most people when we are insulted.
The Malbim, consistent in his view, Haman is saying that it is not worthy of his prestige to kill Mordechai.
In Sichos Mussar, Rav Chaim Shmulevitz writes that physical things are attainable. Honor, however, is not real, is not physical, and is completely in one’s perspective and imagination. Since it is not real, honor can never be realized.
The Ginzei HaMelech brings from the Ne’os Desheh that the last letters of “zeh einenu shava lee” (“this is not worth anything for me”) spell out H-Shem’s Name backwards. According to the Zohar (and quoted by Rabbeinu Bachya in his commentary to Bamidbar), any time the Torah contains H-Shem’s Name backwards, it means He is upset. The Ginzei HaMelech explains that ingratitude (like the kind that Haman is showing here) always angers H-Shem.
The Talmud (Chulin 139b) asks where Haman can be found in the Torah. It responds by quoting the verse in Bereishis (3:11), “hamin ha’eitz” (“from the tree”). R’ Aaron Kotler asks, what is the Talmud really asking; after all, Haman in found in Megillas Esther, every time we shout, “boo!” He explains that the Talmud is asking where Haman’s characteristic of ingratitude is in the Torah. Adam, after being given everything in the paradise known as Gan Eden, ends up disregarding his only restriction by eating from the fruit of the Tree of Knowledge of Good and Evil. That lack of appreciation is Haman in the Torah.